Final answer:
The main purpose of performance appraisal is to evaluate and assess an employee's job performance, provide feedback, and document poor performance if necessary.
Step-by-step explanation:
The main purpose of performance appraisal is to evaluate and assess an employee's job performance and provide feedback on their strengths and areas for improvement. It allows supervisors to communicate concerns and reinforce positive performance, as well as discuss rewards or consequences related to performance. Performance appraisals also serve the purpose of documenting poor performance, which can support decisions regarding employee termination.